1. Field of the Invention
The present invention relates to navigation receivers, and in particular to bootstrap initialization of one GPS navigation receiver with another in tandem.
2. Description of the Prior Art
A variety of global positioning system (GPS) navigation receivers are now commercially available for a number of applications. Each has some advantage over the other that is implemented by changes in the receiver design, especially in those circuits that acquire and track navigation satellites. Land survey GPS instruments are able to achieve millimeter level position accuracies by measuring the carrier phases of individual navigation satellite transmissions. Other receivers are particularly adept in sorting through the multipath signal distortions that occur in cities.
A new breed on GPS navigation receivers has emerged on the commercial market that are able to acquire and track navigation satellite signals that are exceeding weak and faint. Too attenuated for traditional navigation receivers, these highly sensitive receivers use various techniques including “aiding” to acquire and track navigation satellite signals
Ordinarily, only one global positioning system (GPS) navigation receiver would be needed at any one location. So the prior art lacks references to the combining of one navigation receiver that helps another collocated one to initialize. It is far more common for precise frequency references that are locally available to be used to reduce the uncertainty in frequency searches of the satellite carriers. It is also conventional for remote servers with navigation receivers to remotely forward ephemeris and almanac data to reduce code search time and to be able to better predict Doppler.